A projection lens barrel of a projection display device is heated by light from a light source. There has been known a problem that when the projection lens barrel increases in temperature by this heating, optical characteristics of the projection lens barrel change to cause reduction in image quality of a projected image. JP 2008-26864A discloses a projection lens barrel including a correction mechanism that corrects the position of a lens group so as to correct a focal length that changes due to an increase in temperature of the projection lens barrel. However, regarding the reduction in image quality of a projected image caused by the increase in temperature of the projection lens barrel, the image quality reduces not only due to changes in a focal point but also due to other changes in optical characteristics.